Signs Your Pet May Be Sick — and When to Call the Vet

Common Physical Warning Signs

Pets communicate discomfort through physical changes long before they appear visibly distressed. Knowing what to look for puts you in a much stronger position to act early. Visit our Pet Health & Wellness hub for broader wellness context.

Changes in Eating, Drinking, and Bathroom Habits

• Appetite loss: Skipping one meal occasionally may be normal, but persistent refusal warrants a call to your vet — especially in cats, where even 24–48 hours without eating can lead to hepatic lipidosis (fatty liver disease).
• Increased thirst or urination: Noticeably more trips to the water bowl or litter box can indicate kidney disease, diabetes, or hormonal disorders. This is sometimes called polydipsia/polyuria.
• Vomiting or diarrhea: An isolated episode is often minor, but repeated occurrences — or vomiting/diarrhea accompanied by blood, lethargy, or abdominal pain — require prompt veterinary attention.

Physical Appearance Clues

• Weight loss or gain: Unexplained changes in body condition over weeks are a meaningful signal, not just a cosmetic concern.
• Coat and skin changes: Dull fur, flaking skin, patchy hair loss, or persistent scratching can point to allergies, parasites, hormonal imbalances, or nutritional deficiencies.
• Discharge from eyes or nose: Watery or colored discharge — particularly if thick or accompanied by sneezing, coughing, or squinting — may indicate infection or respiratory illness.
• Distended or painful abdomen: A bloated belly, especially in dogs, is a potential emergency. Gastric dilatation-volvulus (GDV) is life-threatening and requires immediate care.

For a deeper look at subtle discomfort cues, see our article on signs that a pet is in pain.

Behavioral Changes That Signal Illness

Behavioral shifts are often the earliest clue that something is wrong — and the easiest to miss. Animals, especially cats and prey species like rabbits and guinea pigs, instinctively mask weakness. Understanding normal behavior for your individual pet is the baseline.

Key Behavioral Red Flags

• Lethargy or unusual withdrawal: A pet that suddenly stops greeting you, hides persistently, or shows no interest in play or food may be ill rather than simply moody.
• Aggression or personality changes: Sudden irritability, growling when touched in a specific area, or unprovoked aggression can signal pain. This overlaps with the Animal Behavior hub on how pain and anxiety shape conduct.
• Vocalization: Excessive meowing, whining, or crying — especially at night or when touched — often indicates discomfort or cognitive decline in older pets.
• Changes in grooming: Over-grooming (creating bald patches) or complete grooming cessation are both abnormal. Stress, pain, skin conditions, and systemic illness can all be responsible. Our guide on stress and anxiety in pets covers overlapping behavioral signals.

A Note on Senior Pets

Older animals develop age-related conditions — arthritis, cognitive dysfunction, vision loss — that can look like behavioral problems. If your pet is entering its senior years, our article on keeping a senior pet comfortable outlines what to watch for and when to seek care.

When to Call the Vet — and When to Go Immediately

Not every symptom is an emergency, but some demand immediate action. Use the guidance below for general triage — when in doubt, call your veterinary clinic. Most practices offer phone guidance to help you decide urgency.

Go to an Emergency Vet Now

• Difficulty breathing, choking, or blue-tinged gums
• Collapse, inability to stand, or seizures
• Suspected poisoning or toxin ingestion
• Uncontrolled bleeding or suspected broken bones
• Straining to urinate with no output — especially in male cats (urinary blockage is a life-threatening emergency)
• Rapidly bloating abdomen in a dog

Call Your Vet Today

• Vomiting or diarrhea more than twice in 24 hours
• Appetite loss beyond 24 hours (dogs) or 24–48 hours (cats)
• Limping or reluctance to bear weight
• Noticeable swelling anywhere on the body
• Cloudy eyes or sudden changes in vision

Schedule a Routine Appointment

• Gradual weight changes over weeks
• Mild coat or skin changes without other symptoms
• Slightly increased thirst or urination

Routine checkups catch problems before symptoms escalate. Our article on annual wellness visits explains exactly what vets look for — and why routine exams matter even when your pet seems fine. You may also want to read about veterinary visits that owners often skip to stay ahead of common gaps in preventive care.

This article provides general educational information about pet health and is not a substitute for professional veterinary advice. Always consult a licensed veterinarian for concerns about your individual pet's health.